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698K views 6K replies 208 participants last post by  Red Five 
#1 · (Edited)
The number of Devastator versions and the number of documented Devastator builds is multiplying, it would be nice if some of this information were kept more neatly in one place. This thread is a work in progress. I will add new variants to this thread and also builds and link them below. :cool:

As always, in the pursuit of performance from the use of wood! Wood is still cheaper than amps and sub woofers.... Let's not forget the other part of the Devastator formula, simplicity! (remember we are dealing with a band pass here, they are more complicated). No diagonals, all panels are on right angles to simplify the building process.

Note: there are also some guides linked below in this post. If you have questions about how to assemble a Devastator, there is a lot of good information in the builds, do this and do not this. That is on top of the build guide. Basic assembly works its way from the top and front panels, towards the back and downwards. Top hatches, rear panel vents, high compression fronts and Stepped fronts have all be added as the Devastator has evolved. Items are listed for the most part in Chronological order. Several members have put a lot of time in documenting the build process. Please check out their build threads!

Want to design a Devastator all on your own? The Hornresp tutorial is posted below. If you have design questions feel free to post them in that thread! There are tools for helping design cabinets in Google Sheets posted in that thread too.

With the addition of the Stepped front Devastators, responses can be mostly flat natively. Knowing your room and what can fit in a space are going to be key factors for selection vs trying to leverage the response shape in spot the suites the box well.

Suggestions for box selection: Devastators have seen evolutionary progress as time has gone on. The biggest factor for selecting a Devastator is the space available. That is one of the main driving factors for the wide array of designs beyond achieving more performance from the use of building material. Room size is another big factor. (I grabbed this from Audioholics)

Room
Dimensional Volume
Small Room​
< 1,500 ft^3​
Medium Room​
1,500 ft^3 to 3,000 ft^3​
Large Room​
3,000 ft^3 to 5,000 ft^3​
Extreme Room​
> 5,000 ft^3​

Small room, you can probably get away with a couple Micro 15" Stepped V1s. Medium room, you will need a couple 18"s at least. Large room - 21"s. Extreme, how many Fat Boy V5s can your marriage take? Other factors, is the room open to other areas and is it an odd shape? That can mess with the equation especially if sub placement options are limited.

Why bass physics suck:

Below is the Fat Boy Version 5 with the native 22Hz tune in gray and I tweaked the vent area down so it is now tuned to 18Hz. As you can see from the graph output takes a huge 5db hit from the lower tuning. In room that 22Hz box will probably stick with all the other Index Devastators down to 17Hz or 18Hz. That is a bit room dependent, so your mileage may vary. Also, remember 6db is the equivalent of doubling your sub system, amps, boxes and sub woofers, 3db from cone area and box displacement and 3db from the input power doubling.

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Now I am going to push this further down to 15Hz tuning on the rear chamber. As you can see we are down a solid 10db on the left corner from the original 22Hz tuning and another 5db from the 18Hz tuning.

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The important thing to know? Each octave (dividing a given frequency by 2) you descend in frequency will require 4 times the displacement to achieve a given level of output. Let's say when tuned 20Hz a box can hit 88db on 1 watt of power with 1mm of excursion. If we tune the box to 10Hz it would take 4mm of excursion from the woofer to hit 88db. This is an important fact when selecting a Devastator. There are three factors that will come into play. Output, Extension and Cost, those factors will always have to be balanced. You can chose 2, but you cannot get all 3 unless you are in a very small space that gains very well. A 7000 cubic foot room on a concrete slab is not a good place to chase extension. It would be better to go with higher tuned cabinets and gain the wobble effect from a BOSS platform. Unless you have the luxury of unlimited budget.

High Pass Filter Orders:

Real quick rundown, 6db of slope is an order. For example a 2nd order Butterworth filter will knock the response down 12db per octave. If set to 20Hz the response will be down 12db at 10Hz, assuming it is applied to a flat line. 2nd order filters can make integration easier in certain circumstances. Especially if the cabinet tunes have a wider range than just a few Hertz. Integration with sealed cabinets can be more tiresome and require a lot of trial and error. An 8th order 48db per octave slope on the sealed cabinet and then using a 2nd order HPF a few Hertz over tune on the Devastator can be a good starting point. Once again YMMV. If you do plan on using a 2nd order filter, go a little over tune with the filter to control driver excursion below tune.

Order: (typically you will not see a Dev go over a 4th order, just keep multiplying by 6 to go up)
1st 6db per octave
2nd 12 db per octave
3rd 18db per octave
4th 24db per octave

Why do we need High Pass Filters on a Devastator?

Below the tuning frequency of the Low Frequency(LF) resonator cone excursion goes out of control(see example below). The cone is no longer seeing a load like it would above the tuning frequency of the LF resonator. The cone movement would be similar to the sub being given power in free air. A pro driver can take several hundred watts in most cases in free air when sent a low frequency waveform. Doing that to a woofer frequently could A. damage the woofer over time and B. if sent a more powerful signal could bottom the woofer out immediately. The High Frequency (HF) resonator does present some load to the woofer below the LF tuning frequency, but it is not enough to control the cone movement. DO NOT RUN your Devastator without a protective high pass filter.

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As you see in the graph above, the cone motion with the 2000 watt input on this NSW6021-6 has the driver well outside of the 21mm xmax below 20Hz. Once a Butterworth 18Hz 4th order high pass filter is actived the cone is peaking around 19mm below 20Hz(light gray line) and that is inside the NSW6021-6's rated xmax.

Slang/Terms:

HCR - High Compression Ratio. This front has a bell curve, but is not quite as peaky as a lower compression front and uses less space. Good for shallow cabinets.
TR - Tactile Response
Stepped - A front quarter wave resonator with 2 or 2+ cross sectional areas. The response is typically more flat and they gain more low end output.
BR - Bass Reflex
QW - Quarter Wave resonator. These are typically referred to as horns. On a Devastator they do the high frequency lifting.
FPR - First Port Resonance
BB - Baltic Birch plywood. (not the veneer box store stuff, call a lumberyard)
BBv1 - Big Boy Version 1
MLP - Main listening position.
REW - Room EQ Wizard.
HPF - High Pass Filter.
BW - Butterworth.
LF - Low Frequency
HF - High Frequency
HO/SHO - High Output or Stepped High Output. Usually these cabinets have 22Hz tuning.
BMD - Beast Mode Devastator. Typically they are closer to 60" height vs 48"
FV - Finalizer. This cabinet started as a 48"x25.5"x34" cabinet with lower tuning. FV can be used for the 16Hz tuned rear chamber or the form factor
Dev - Devastator. Generally cabinets that are around 48" in height.
Mini - Typically this cabinet type is around 40" in height.
Micro - Usually in the above or around 30" in height.
Nano - Usually used for 12" cabinets.
FB - Fat Boy. Typically as deep as they are wide.
BAMF - Bass Ascension Module Five. Home music or PA cabinet with higher tuning and a Stepped QW resonator.
NSW - Eminence NSW6021-6
SAN - Lavoce SAN214.50 or the SAN215.30 is another good choice, but not usually that is referring to the 214.50.
DS - That could be a B&C 21DS115 or a 18DS100-4, both are great choices.
TBW - B&C 18TBW100 is usually the reference, but the 15TBW100 is another good woofer.
SAF - Lavoce SAF184.03
WAF - Should be the Lavoce WAF154.00
D21V6 - This would be an example the Devastator 21" version 6
M18V6 - This would be an example of the Mini Devastator 21" version 6
FB21V5 or FBv5 - Fat Boy Version 5
FV1 - Finalizer Version 1

Devastator response evolution:

The Devastator has seen developments over time. The examples below are on 48" tall cabinets to show the three main fronts and how they affect the response.

The Devastator 21" Version 1 is the first Devastator designed by John. As you can see the front HF QW resonator adds SPL across the entire frequency range, peaking in the mid bass region. Light gray is ported cabinet with the same vent length, vent area and chamber volume as the D21V1.

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Next up we have the Devastator 21" Version 5 with an HCR front. The HCR front has a smaller cross section area vs the lower compression front, but still adds output across the range and takes up less space in the cabinet. Once again dark gray is the V5 and light is just a basic BR chamber with the same specs.

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Finally we have the Fat Boy Version 5 with its Stepped QW resonator that has multiple cross sectional areas. The higher tuning coupled with the design of the QW resonator makes the cabinet very flat and efficient. The higher tuning also allows the resonators to be spaced 1 octave apart in frequency without cutting our top end short, so this design can still crossover at 80Hz into a sound system.

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Other advantages to having the front QW resonator:

Cone protection from curious children, pets and sometimes friends that are tipsy. Less rear chabmer/motor noise, the panels dampen noise that would otherwise find its way through the cone and into the room. Obviously the QW resonator eats up more space vs having nothing in front of the woofer, but the QW resonator has a few things going for it.

Construction/material/tips:

The preferred building material is currently expensive. Baltic Birch plywood (not the veneer stuff at box store, call a local lumber yard) is the preferred building material. 18mm is close enough to 3/4" not to mess up the building process. MDF is heavy and makes a big dust mess and does not take screws well, tends to crack. ACX plywood is lightweight, but has voids and a tendency to warp. BB is lighter than MDF and does not make the dust mess and is less prone to warping and also voids. MDF also sucks for using Kregs.

If you have router with a flush trim bit, it is not a bad idea to add 1/8" inch on the side panels and then clean it up after assembly.

PL3X is the glue of choice due to how forgiving it is with voids and set time. When using PL, wear gloves, you do not want that stuff getting on your skin and it will mess up clothing. If you are a fluent wood worker, you do not have to say no to tight bond.

Marking panels before assembly is another pro tip. I would also suggest marking up the woofer cutout and drilling all the holes for fastening the woofer before assembly. Marking the panel alignments/positions on the side panel, front panel and baffle are all good ideas. Measure twice, cut once is another good rule to live by.

Air leaks around the access panel are usually the number one issue once the box is together. Especially if the measured response looks weak on the left corner. If you want to make sure you have a good seal, turn off the lights, put a flashlight in the rear chamber. Button the hatch up and look for light coming through the hatch seal. Weather stripping or the PE gasket tape will work.

If you have a question or are unsure of something when putting the cabinet together, feel free to post the question in the Index. This thread has large following that is happy to offer tips!

Bracing - here is a good example of a common bracing mistake. The wider dimension should be adjacent to the outside panel, like in the photo below.

Driver mounting - Chris made this write up for his technique for securing the sub to the baffle - link



Threaded Inserts (Sub woofer mounting solution)

Panel Names?


Below is a reference image
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Rear Chamber Resonance/dampening material

Chris when testing the JBL Quad Devastator did some measurements with different pillow configurations in the rear chamber. We also reached out to a few members for measurements they took. It would appear standing waves in the rear chamber start to encroach on the passband somewhere between 40" and 48" of rear chamber length. Boxes close to 48" on up need pillows tacked onto the side panels to alleviate near past band resonance. The goal is having a clear path from the back of the woofer to the vent inlet. Air restriction will hurt low end output. However, if there is minimal restriction in air movement, a minimal loss in low end output will take place. Here are the links to the Quad testing.

Resonance Testing Pt1
Resonance Testing Pt2

Does my UM18/IB/high Qts Sub work in a Devastator?

The short answer is no, it does not work in a Devastator. This is a UM18 in a Mini Devastator 18 Version 6.



As you can see the woofer gets a very sharp peak at the resonant point of the front horn of the cabinet. You might be thinking why not just EQ that peak? Here is the problem, the UM18 will ring when loaded in a Devastator, the cone stays in motion after a impulse. This is the UM18 vs the 18TBW100, pink is the UM18, green is the TBW. Notice how the cone on the TBW stops moving relatively quickly. Some subs are designed to work well in higher order band pass boxes, others are designed to work in lower order band pass boxes. There is a simple method for finding a good woofer using a specific metric. Efficiency Bandwidth Product (EBP), the woofers Fs value divided by its Qes value. The Devastator starts working once a value gets around 70 or so. Values closer to 100 are better, but not absolutely necessary. If you have a woofer with a value higher than 70 and are curios to see how it looks, just post a message in the thread :)



Any Devastators optimized for music?

Yes, the BAMFs are designed to handle music duty/PA use. There are currently three different versions available with different tuning depending on the needs of your system. If interested I have a smaller design meant for an 18" that will definitely make some loud noise that has not been released yet.

I bought a Crown amp that has a network card, how do I manage it???
Chris made a nice write up concerning this situation, you can find it right here. You will need the Harmon Audio Architect software installed on computer that is on the same network as the USP card.

Reference Port Plug Design - link

Performance data (HR Estimations GP1m):
The Big Boy Family 21"s
The Fat Boy Family 21"s
The Finalizer Family 21"s
The Alpha Family 21"s
The BAMF Family 18"s + 21"s
The BMD Family 21"s
The Mini Devastator Family 21"s
The Devastator Family 21"s
The Mini Devastator Family 18"s
The Devastator Family 18"s
The BMD Family 18"s
The Micro Devastator Family 18"s

Shallow + Narrow 21" + 18" Devastators

Common 21 Comparison Graphic (shoutout to Chris for his help with this)
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Common 18" Comparison Graphic
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Current (9-1-22) top picks!
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Note: The Alpha III and IV have narrow clones. The FBv6 has a narrower clone and the 18BMDSV2 has a clone.

PLEASE SHARE BUILDS IN THIS THREAD!!! (including pictures)

Designs (Guide is near the bottom of this post and see build links, a lot of go information in there.)

Broken down by woofer size:

24"
21"
18"
15"
12"
Build threads/other
Guides
 

Attachments

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18
#5,314 ·
Here is a chance for some feedback. I was currently eyeing asymmetrically spaced port rails on the 22Hz version of the Punisher in order to hit the desired tunes of 16Hz and 19Hz depending on how many ports were plugged and which ports. A 13in port with a neighboring 4.5in port and a 4.75in port looks really wrong. I could add an additional rail on the vent in order to make the gap look way less crazy. The tuning was a bit lower than I wanted with the quad vent openings, but it was in the ball park.

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This begs the question of, does it really require 3 version due to that last db sitting on the table or does the flexibility of shifting tunes make up for the small lose of performance? If the 21.5Hz tune is not low enough, plug the port and drop down a bit over 18Hz and if that is still now low enough, drop down to a little under 15Hz... (I was not intending to copy the SK, it just looks way less weird this way... Unlike the SK, I am intending things get plugged to lower tuning) The extra rail took the tuning down a little on the 22Hz model, closer to 21.5Hz than 22Hz.
 
#5,315 ·
Quick newb question: does it matter in which direction the port and horn are firing? I thought I was set on the BMD Shallow Mini Hybrid, where the port and horn would face the MLP. But the BMD Shallow DF might have a better aesthetic for my room, and the curve looks nice, with a bit more punch at 20-50Hz. The only thing is, the port and horn would be firing 90 degrees from the MLP.

My 4-ohm SAN is arriving tomorrow, and I will purchase the MDF and things today.

Suffering from analysis paralysis.
 
#5,316 ·
Frequencies this low do not care much about the direction in which something is pointed. Sound pressure should be okay, you might lose some of the particle movement effect. Since the vent/mouth are not pointing directly at you. However, I do not have any data to back that assumption up.
 
#5,319 · (Edited)
@Red Five do you have a file for The Big Boy Version 10 (Tree Saver) ? im looking to get it into my 3d program and work off your volumes and such for aero ports and different shape
to give you an idea of what im working with. i have this as my total maximum space. id like to slant the sides height wise - so they sorta blend towards the wall more but that will depend on total volume needed of course.
this is about 38.3 cubic feet
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#5,321 ·
The front resonator on a Devastator does not operator based on chamber volume, vent area and length. It is based on resonator length and cross sectional area at specific points. So, a quarter wave resonator vs Helmholtz resonator. This tends to complicate the outlet/mouth locations on the box. Since the folds on the QW can only work so many different ways. What's the specific need on the cabinet for heavy modifications? I won't have access to the CAD files for a bit.
 
#5,325 ·
I haven't had time to investigate fully, but I am assuming the quad barrel ports will knock the tune down in the same increments on other designs. Knowing that I would visit the 22Hz behemoths. Alpha III and the BBv10... I am assuming it will work the same way as the Punisher. Slight decrease in low end output in exchange for flexible tuning. Which allows for adapting to room circumstances. If you have great room gain dumping the tune a lot is an option or small room leads to low tuning, medium room middle tuning and finally large no gain room leave the 22Hz tuning.
 
#5,330 ·
JBL QUAD 12" DEVASTATOR BUILD 48"x28"x28" cabinet
Hi everybody!
I am working on my first devastator build and was about to order my drivers but I'd like to hear what you guys would suggest.
I live in Belgium, the super cheap 12" JBL car subwoofer sale is not a thing here, so I am looking to spend about 80$ per driver.
Now there are two options (i added a spec sheet of both):
-GRS 12SW-4HE 12" subwoofer (250W RMS, 4 Ohms, 84.5 dB sensitivity, 20-500Hz)
-JBL Stage 122d 12" subwoofer (250W RMS, dual coil 4 Ohms, 91 dB sensitivity, 34-200Hz)

Which one of these two would suit my project best?
In both cases I would wire the four drivers in series-parallel, for the GRS resulting in a 4 Ohm impedence, for the JBL resulting in a 8 Ohm impedence.
From what I understand the JBL's output would be quite a lot higher due to it's higher sensitivity.
The GRS on the other hand have a significant better response in lower frequencies.

I would use the devastator in combination with two fullrange speakers (JBL JRX125) mainly for playing music, but I'd want a good bass response around 30Hz too. That should be possible with the JBL drivers too, looking at the results from other devastator builds that use JBL CS1214 or JBL GX1200 drivers that are quite similar to the JBL stage 122d drivers I am looking at. The only difference is that those ones are not a dual coil design.

I am new into the whole speaker building thing so don't get to complicated please :)

Jules
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#5,331 ·
JBL QUAD 12" DEVASTATOR BUILD 48"x28"x28" cabinet
Hi everybody!
I am working on my first devastator build and was about to order my drivers but I'd like to hear what you guys would suggest.
I live in Belgium, the super cheap 12" JBL car subwoofer sale is not a thing here, so I am looking to spend about 80$ per driver.
Now there are two options (i added a spec sheet of both):
-GRS 12SW-4HE 12" subwoofer (250W RMS, 4 Ohms, 84.5 dB sensitivity, 20-500Hz)
-JBL Stage 122d 12" subwoofer (250W RMS, dual coil 4 Ohms, 91 dB sensitivity, 34-200Hz)

Which one of these two would suit my project best?
In both cases I would wire the four drivers in series-parallel, for the GRS resulting in a 4 Ohm impedence, for the JBL resulting in a 8 Ohm impedence.
From what I understand the JBL's output would be quite a lot higher due to it's higher sensitivity.
The GRS on the other hand have a significant better response in lower frequencies.

I would use the devastator in combination with two fullrange speakers (JBL JRX125) mainly for playing music, but I'd want a good bass response around 30Hz too. That should be possible with the JBL drivers too, looking at the results from other devastator builds that use JBL CS1214 or JBL GX1200 drivers that are quite similar to the JBL stage 122d drivers I am looking at. The only difference is that those ones are not a dual coil design.

I am new into the whole speaker building thing so don't get to complicated please :)

Jules View attachment 3411884
View attachment 3411883
Redfive modeled the quad 12 with the GRS woofers for me quite a while back, and I thought about upgrading my cabinets to those woofers. I didn't do it, but I would lean that way given those two options.
 
#5,335 ·
@julesfocke Welcome to AVS!
I can't help you with your question, except to point you towards @jmilleril who you've already seen reply, and @Red Five, the guru behind using these drivers in a Devestator enclosure.
My real reason for saying hi is that you are probably the only other person besides me that have used, and by the looks of it, you still use, those JBL JRX125's!
I bought mine about 15 years ago. I had a cat that loved to use them as a scratching post until I cranked them up, then he would run! But he always came back for more, plus he loved to sleep on top of them. They still have fur in them all these years later.
While they are not high quality drivers, they do a pretty good job. Mine now just sit in my shop collecting dust once again, I just can't get myself to sell them. Terrible low end bass response, but they were not designed for that.
I also have the matching 18" self-powered sub that goes with them.
Again, not a low end monster.
All of that gear is for 40Hz and up, and it does just fine there. A local school (back then) used that same setup in their auditorium, I think it had 200 seats, maybe more. I used them in an 11x15 room! :)
 
#5,337 ·
@julesfocke Welcome to AVS!
I can't help you with your question, except to point you towards @jmilleril who you've already seen reply, and @Red Five, the guru behind using these drivers in a Devestator enclosure.
My real reason for saying hi is that you are probably the only other person besides me that have used, and by the looks of it, you still use, those JBL JRX125's!
I bought mine about 15 years ago. I had a cat that loved to use them as a scratching post until I cranked them up, then he would run! But he always came back for more, plus he loved to sleep on top of them. They still have fur in them all these years later.
While they are not high quality drivers, they do a pretty good job. Mine now just sit in my shop collecting dust once again, I just can't get myself to sell them. Terrible low end bass response, but they were not designed for that.
I also have the matching 18" self-powered sub that goes with them.
Again, not a low end monster.
All of that gear is for 40Hz and up, and it does just fine there. A local school (back then) used that same setup in their auditorium, I think it had 200 seats, maybe more. I used them in an 11x15 room! :)
The reason for my question here was actually because of a full project I am doing with my JRX125's :) they are indeed ****ty on the low end. This is my first audio project and I am keeping everyting cheap (bought the JRX with an American Audio VLP1500 amp and Behringer equalizer for 400$; looking to expend about 600 on the devastator and the new cabinets I made for the JRX speakers). The new cabinets for the JRX speakers have a design inspired by the Altec 816 cinema speakers, with front loaded horns and bass reflex which I will use from 100Hz and up. I modeled the cabinets in WINISD for optimal ports and cabinet volume for the m115-8a drivers that are in the JRX speakers. The tweeter 'horns' are the original JBL waveguides, just mounted on top of the cabinets. The devastator will come in handy for everything happening below 100Hz. To power it all with the VLP1500 with about 2x500W I will have to make everything mono and power the devastator with one channel and split the signal of my other channel into the JRX speakers. As a crossover I will be using a behringer super-X pro cx3400 V2. Later on I might add extra amplifiers/speakers to the system, this is just a start. I added my sketchup design so you can see what it looks like!
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#5,346 · (Edited)
Punisher - Wood Saver - Flex Tune
The Punisher is an absolutely ridiculous ship in the Xwing Miniatures game, holding a lot of explosive ordinance with 4 distinctive fuselages for munitions vs the single extra fuselage found on the Tie Bomber(like Chris said, this should have been the name for the Quad JBL). This design does have a quad barrel port, so close enough. The quad divided vent adds a lot of flexibility for hitting a desired tune ~15Hz, ~18Hz and ~21Hz depending on the port configuration. Chris built very nice looking port plugs, I checked his Alpha build thread, but I did not find them in there. For testing or hack job purposes you can find foam yoga blocks if you look around on Amazon. If you are unsure of what you are looking for in your sub system, this is a pretty safe bet due to its adaptability. There will be three sets of simulations, one for ports all open, 1 plug and 2 plug configurations. The NSW will be running with 1000 watts of input power for the simulations. Excursion looks well controlled and velocity control also looks good, so power handling is an above average amp if running the native 21Hz tune. Mechanical limits will be more prevalent as tuning goes down vs how much can this thing take before it turns into a stinky slinky? I have a lot of graphs in this one, if someone wants to know what kind of power it takes to hit xmax, drop a post!

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1000 watts all open, HPF BW 18Hz 4th order

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1000 watts 1 port plug HPF BW 16Hz 4th order

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1000 watts 2 plug HPF BW 14Hz 4th order

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Spacing on the port rails is 5 3/8", the mouths on the QW resonator are 7.5 on the outsides and 7.25 on the inside. (it is a really messed up number and not a good fraction)

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#5,347 ·
Alright @Red Five, I`ve got to ask the output at xmax for the different tunings, and the power to get there. You`re doing the HT crowd a genuine service, thanks.
 
#5,348 ·
79 volts - 1.64 kw to 21mm above LF tune
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86 volts - 1.95 kw to 21mm above LF tune
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93 volts - 2.28 kw to 21mm above LF tune
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If you are one of those people that get room gain, power input potential will go up substantially. A 3db cut from EQ just halved power input. Above the low frequencies the game turns into how much voltage can your amp put out and how much heat can the coils withstand. Or just get more subs....
 
#5,354 ·
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This is the current concept for the Alpha V, it consists of tweaks to the Alpha III for updating with the quad barrel port and also increasing the vent length vs the Alpha III.
 
#5,355 ·
I have a ways to go, but this is where I landed with the Alpha V. I tweaked the vent a bit more.

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#5,363 ·
#5,365 ·
This isn't devastator related but might be helpful to Red Five as he helps others. There's been talk of Cleanbox Pro's having a rolloff at 20Hz, so as I'm tinkering with my sealed HS-24 I did an experiment. Here are nearfield measurements I took of my HS24 about 2" from the center of the dustcap. Audyssey on and mains crossed over at 250Hz. Ignoring room affected results of the HS24, The green is the miniDSP connected directly to a Crown CTS-3000 and red is with a Cleanbox pro in the mix. Everything was the same except I adjusted the output on the Cleanbox to match the upper frequency range to the measurement without. I also tried an Aphex 124a (in blue) and it doesn't seem to roll off like the Cleanbox. The Aphex doesn't appear to have the control to fine tune like the Cleanbox (unless user error is in play), so I had to adjust the volume on the AVR to similarly match the response. Not exactly apples to apples, but the Aphex doesn't seem to show the same roll off like the cleanbox does.
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Attachments

#5,366 ·
Thanks for that! I thought my Rolls Pro Match had big time roll off vs the 124A on the low end. This was before I had a microphone and I do not have the ambition to dig it out of storage in right now.
 
#5,367 ·
@Red Five - not seeing anything for a single 12” JBL DEV… and I’m sure there is good reason for that. I have a pile of scraps and a stack of JBLs and I was thinking about making a few cabs with single JBLs in them as gifts for a couple HT friends that always tell me that they want DEVs like mine… so it’s kind of a gag gift - but only if they’ll not be a complete waste of time. Will that driver do anything on its own in a DEV and could I just shrink down a D21V1 box to 12” scale or would you recommend a different enclosure completely?
I just read @a77cj7 ’s quad JBL thread (again) and I could go that route, but I already have enough real bass in my theater. This is more for screwing around. The leftover drivers will be BOSS’d.

Any help is greatly appreciated.
 
#5,368 ·
@Red Five - not seeing anything for a single 12” JBL DEV… and I’m sure there is good reason for that. I have a pile of scraps and a stack of JBLs and I was thinking about making a few cabs with single JBLs in them as gifts for a couple HT friends that always tell me that they want DEVs like mine… so it’s kind of a gag gift - but only if they’ll not be a complete waste of time. Will that driver do anything on its own in a DEV and could I just shrink down a D21V1 box to 12” scale or would you recommend a different enclosure completely?
I just read @a77cj7 ’s quad JBL thread (again) and I could go that route, but I already have enough real bass in my theater. This is more for screwing around. The leftover drivers will be BOSS’d.

Any help is greatly appreciated.
Look for Nano Devastator. It is on page one under 12" builds.
 
#5,369 ·
I finished my 21" Shallow Mini Hybrid HCR and finally did a write-up. Comments and constructive criticism are most welcome.

 
#5,371 ·
While I'm fine tuning my setup, I thought this data might be interesting as well. It's been mentioned that the Crown XLS amps roll off at 20Hz, so I ran nearfield measurements on my sealed HS24 with an FP22000Q, Crown XLS-2002, and Crown CTS-3000 amps. Perhaps I'm wrong, but my assumption would be if a HPF of some sort were applied to the amp that it would show up with a sealed HS-24.

Measurements taken with the crossover set to 250Hz and Audyssey off on my AVR. There's no cleanboxes in the middle and gain tweaks were done on the attenuation on the FPQ-22000Q and then on the miniDSP input for the crowns. Take this data for what it's worth, but here are my results:
Rectangle Slope Plot Font Line


I posted measurements with the same type of test a page or so back that make it appear than perhaps some sort of HPF around 20Hz is applied with a cleanbox, but this doesn't seem to be the case with the crown amps. There are minor differences below 10Hz, but sometimes results down that low vary for me. I also wonder with what appears to a a HPF on the Cleanbox if perhaps instead of writing it off, someone could do measurements and just adjust the filter used on a miniDSP along with gains to overcome that filter?
 
#5,373 ·
Has anyone integrated a Devastator and sealed setup? It had been mentioned Dev's have a similar GD as sealed do?

I am tossing around utilizing a pair of mini DEVs from 80 down to around 30 or so, and letting the sealed take over from there. With room gain my subs are dead flat to 5hz.

Next question, if they will play nice together: What would be the recommended DEV, that fits in a 24 x 26 x 40ish footprint? I have subs flanking my C behind screen, and would stack the 2 dual sealed on top of the DEVs.
 
#5,381 ·
I don't know what your tool situation is, but if you are like me, and using a track saw and a chop saw, the bracing cuts will drive you nuts. If you have a table saw, then, carry on!

I always cut full length strips for my braces, and then cut them to exact length as the build progresses. If the cabinet happens to grow by a bit, you can't easily add material back on with this layout.

Although I have found since I attach the braces to the panels before making the panels into a box, this doesn't happen anymore. The panels locate against the braces, and get glued to them as part of it, yielding better glue joints. This also allows for optimum clamping and gluing of the braces to the panels, instead of whatever you can muster in a brace after build scenario. Obviously this all requires the cuts to be right at the right size, so your mileage may vary on that if you aren't routinely holding under a 1/16th.
 
#5,382 ·
I've got a track saw, compound miter, table saw, two jessam lift router tables, a planer, couple handheld routers, and a whole bunch of white side bits.

I'm also planning on cutting holes in the side to put handles. I ordered some big DJ cabinet handles to go in. Figure I'm going to put some sound damping material over them on the inside
 
#5,386 ·
Rectangle Slope Font Plot Parallel


I would not recommend it. Too much mass, low Fs, not enough energy. It looks good for ported or sealed applications.
 
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